Gas turbine ducts exposed to elevated temperatures in operation must face differential thermal expansions. For example, where airfoils span the duct, the airfoil may be exposed to the hot gas flow which causes it to expand radially. However, the airfoil is radially restrained between the two rings of the respective inner and outer walls which are cooler than the airfoil because the inner and outer annular walls are protected somewhat by the developed boundary layers of the hot gas flow and may be further cooled by external and secondary airflows. This results in a thermal mismatch which may generate stress on the adjoining areas of the outer and inner annular walls. There is a need to provide an alternative vane structure of a gas turbine engine for elevated temperature operation.